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Directed Reading A
Section: Moons
1. Natural or artificial bodies that revolve around larger bodies such as planets
are called
.
2. Except for Mercury and Venus, all of the planets have natural satellites
called
.
3. What is the difference between a moon and a satellite?
LUNA: THE MOON OF EARTH
______ 4. How old were the lunar rocks brought back by the Apollo missions?
a. 3 billion years
b. about 3.8 billion years
c. about 4.6 billion years
d. more than 5 billion years
5. What does the age of these rocks tell us about our solar system?
6. What happens to impacts on the surface of bodies without an atmosphere?
7. What were the three popular explanations for the moon’s formation?
8. What is the current theory about the origin of the moon?
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Directed Reading A continued
9. What evidence supports the current theory about the origin of the Moon?
10. Describe how the moon’s appearance changes during the month.
11. The different appearances of the moon due to its changing position are
called
.
12. What causes the different appearances of the moon?
13. Why do we always see the same side of the moon from Earth?
14. When the moon is
, the sunlit part of the moon that
we can see is getting larger. When the moon is
the
sunlit part of the moon that we can see is getting smaller.
Match the correct description with the correct term. Write the letter in the space
provided.
a. eclipse
______15. when the moon’s shadow falls on part of
the Earth
b. solar eclipse
______16. when the shadow of Earth falls on the moon
c. lunar eclipse
______ 17. when shadow of one celestial body falls
on another
d. total solar eclipse
e. annular eclipse
______18. when a thin solar ring is visible around the
edge of the moon
______19. when the moon’s disk completely covers
the sun
20. Why don’t we see solar and lunar eclipses every month?
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Directed Reading A continued
THE MOONS OF OTHER PLANETS
______21. Which of the following statements about moons in this solar system is
NOT correct?
a. Some orbit their planet backwards.
b. Many may be captured asteroids.
c. Some have very elongated orbits.
d. None is as large as the terrestrial planets.
______22. Why do scientists think the Martian moons may be asteroids caught by
the planet’s gravity?
a. They are very small moons.
c. They are similar in composition.
b. They are very dark.
d. They are oddly shaped.
______23. Who discovered the four largest moons of Jupiter?
a. Copernicus
c. Ganymede
b. Galileo
d. Mercury
24. Why is Io the most volcanically active body in the solar system?
25. What evidence supports the idea that life could have evolved on Europa?
26. Why might Titan hold the key to learning more about the origin of life?
27. Uranus’s moon, Miranda, has a surface that is a patchwork of
,
, and
.
28. Neptune’s largest moon, Triton, has a
,
or “backward,” orbit.
29. Pluto’s moon, Charon, has a period of revolution of about
days, and eclipses Pluto once every
years.
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TEACHER RESOURCE
13. Early in its history, Uranus may have
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
been struck by a massive object that
tipped it over on its side.
D
Great Dark Spot
A release of thermal energy causes the
warm gases to rise and the cool gases
to sink, and produces wind patterns
that create the belts of clouds.
A
B
D
C
nitrogen, water
Charon is more than half the size of
Pluto.
Pluto is so small and unusual
compared with the rest of the outer
planets. It is more like a large asteroid
or comet.
SECTION: MOONS
1. satellites
2. moons
3. A moon is always natural, but a
12. These are caused by the changing
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
satellite can be artificial.
4. C
5. Since the rocks seem to be unchanged
6.
7.
8.
9.
10.
11.
since they were formed, the solar
system must be about the same age.
Without an atmosphere, they are
preserved unchanged.
One explanation is that the moon was
a separate body captured by Earth’s
gravity. A second explanation is that
the moon formed at the same time and
from the same materials as the Earth.
The third explanation is that the newly
formed Earth was spinning so fast that
a piece flew off and became the moon.
The current theory is that a large
Mars-sized object collided with Earth.
Part of the Earth’s mantle was blasted
into orbit around the Earth to form the
moon.
The composition of the moon rocks is
very similar to the Earth’s mantle.
The moon changes from a dark unlit
face to a thin crescent, to a half circle
to a fully lit circle, down to a thin crescent, and back to the dark face again.
phases
25.
26.
27.
28.
29.
positions of the moon relative to the
sun and the Earth. As the moon
revolves around Earth, the amount of
the sunlit portion of the moon visible
from Earth changes.
Because the moon’s period of rotation
is the same as its period of revolution.
waxing; waning
B
C
A
E
D
The moon’s orbit around Earth is tilted
with respect to Earth’s orbit around
the sun. Thus, the moon usually
passes above or below Earth’s shadow.
D
C
B
Io is constantly being tugged at by the
gravitational tug of war between the
planet Jupiter and its nearest neighbor,
Europa. This causes Io to heat up,
resulting in eruptions.
Recent pictures show that Europa
appears to have oceans of liquid water
beneath its frozen surface. It is
possible that life may have evolved in
these subterranean oceans.
Titan’s atmosphere is thought to be
similar in composition to the early
Earth, when life first evolved here.
plains, grooves, cliffs
retrograde
6.4, 120
SECTION: SMALL BODIES IN THE
SOLAR SYSTEM
1. Answers will vary but should include
comets, asteroids, and meteoroids.
2. B
3. Largely, because of their composition:
rock, ice, and cosmic dust
4. These bodies are leftovers from the
time the planets formed. Each one is a
sample of that early solar system.
Their composition can provide
information on the history of our solar
system.
5. ion tail, dust tail
6. nucleus
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